The US government is calling on the international community to focus more on the
impact of climate change on the oceans, amid growing concern over changes
affecting corals, shellfish and other marine life.

US government scientists have voiced their concern over recent signals that
marine life is under pressure. An enormous toxic algal bloom nicknamed the
“blob”, stretching from the Gulf of Alaska to the coast of Mexico,
has been linked to the
deaths of 30 large whales (Figure 1
right) washed up on Alaskan coasts.

More than 250,000 Pacific salmon have died or are dying, meanwhile, due to warm
temperatures in the Columbia river. Scientists predict that up to 80% of the
sockeye salmon population, which swim up the river from the ocean to spawn,
could ultimately be wiped out.

A
study by researchers from the University
of British Columbia recently found that global fisheries catches were
increasingly dominated by warm-water species as a result of fish migrating
towards the poles in response to rising ocean temperatures.

Ian Perry, a research scientist with the Department of Fisheries and Oceans
based on Vancouver Island, says butterfish, tope sharks, ocean sunfish, even a
finescale triggerfish have all been spotted further north than usual.

Another
UBC study suggests fish are getting smaller as the oceans warm because the
warmer water holds less oxygen.

The U.S.
National Wildlife Federation warned in
advance of the current salmon die-off that a 3oF rise in average
August temperatures would cause up to 20 percent of the streams in the Columbia
River Basin and coastal watersheds of Washington and Oregon to become too warm
for most salmon, steelhead and trout and that global warming will likely
dramatically alter the Pacific Northwest's rivers in which these fish are
spawned, hatched and initially or permanently reside. There will be less winter
snow accumulation, earlier peak spring stream flows, lower summer stream flows
and elevated stream temperatures all of which will be detrimental to the
existence of these species. (In fact this would be a universal consequence of
global warming.)

Most of these conditions currently exist in the Pacific Northwest as a result of
a record low snowpack and as
NOAA has determined, the average global
temperature for July, 2015 was 1.46°F above the 20th century average.

As can be seen
from the
NOAA visual (Figure 2 right), one of the
warmest regions is the one in which Pacific Salmon spend most of their lives.

An even greater
warming threat to fisheries is the cutting off of their food supply from the
nutrients they need to survive by thermal stratification. Phytoplankton are the
base of the ocean food chain and the lungs of the planet in that they produce
half the oxygen we breath.

The
British Royal Society notes, marine
phytoplankton biomass and productivity have been shown to decrease in response
to temperature-driven stratification that isolates the plants, which require
sunlight, from cool, nutrient-rich, deeper, water.

The other threat
to marine life stems from the increasing acidity of ocean waters. Near the
surface concentrations of carbon dioxide in the atmosphere and the water are in
equilibrium. Since the beginning of the Industrial Revolution atmosphericCO2
levels have increased from 280 parts per million (ppm) to 400 ppm.

When CO2 mixes
with water it forms Carbonic acid and since the levels of CO2 dissolved in the
ocean have been increasing so too has ocean acidity.

As the
Ocean portal of the Smithsonian puts it:
Some marine species may be able to adapt to more extreme changes—but many will
suffer, and there will likely be extinctions. We can't know this for sure, but
during the last great acidification event 55 million years ago, there were mass
extinctions in some species including deep sea invertebrates. A more acidic
ocean won’t destroy all marine life in the sea, but the rise in seawater acidity
of 30 percent that we have already seen is already affecting some ocean
organisms.

These threats to
marine life are mitigated with energy production that reduces thermal
stratification and moves the heat
away from the habitat of most aquatic life.